读取两个文件并根据第一个文件的列过滤第二个文件

Question

I have an input file containing the keywords and have csv file that needs to be filtered on those keywords.

Here is my attempt to automate task using python.

import csv
with open('Input.txt', 'rb') as InputFile:
    with open('28JUL2017.csv', 'rb') as CM_File:
        read_Input=csv.reader(InputFile)
        for row1 in csv.reader(InputFile):
            #print row1

            read_CM=csv.reader(CM_File)
            next(read_CM, None)
            for row2 in csv.reader(CM_File):
                #print row2
                if row1[0] == row2[0] :

                    Output= row2[0]+","+row2[1]+","+row2[5]+","+row2[6]
                    print Output

I get just the first row from the file to be filtered. Tried various things but could not understand where I am going wrong. Please point the mistake for me here.

Answer 1

read_Input and read_CM are essentially iterators. Once you loop over them - you are done: you cannot iterate twice. If you insist on doing your way, then you have to rewind to the beginning of the file each time you want to start a new loop and "re-read" the CSV file. Here is a fix:

import csv
with open('file1.csv', 'rb') as InputFile:
    with open('file2.csv', 'rb') as CM_File:
        read_Input=csv.reader(InputFile)
        for row1 in csv.reader(InputFile):
            CM_File.seek(0) # rewind to the beginning of the file
            read_CM=csv.reader(CM_File)
            next(read_CM, None)
            for row2 in csv.reader(CM_File):
                if row1[0] == row2[0] :
                    Output= row2[0]+","+row2[1]+","+row2[5]+","+row2[6]
                    print Output

Instead of this, I would suggest that you loop over already read lines instead of re-reading files. Also, instead of having nested loops, create a list of "keywords" and simply check that row2[0] is in that list:

import csv
with open('file1.csv', 'rb') as InputFile:
    with open('file2.csv', 'rb') as CM_File:
        read_Input = csv.reader(InputFile) # read file only once
        keywords = [rec[0] for rec in read_Input]
        read_CM = csv.reader(CM_File) # read file only once
        next(read_CM, None) # not sure why you do this? to skip first line?
        for row2 in read_CM:
            if row2[0] in keywords:
                Output = row2[0]+","+row2[1]+","+row2[5]+","+row2[6]
                print("Output: {}".format(Output))